Chemicals and fertilizers are commonly applied to agricultural crops. Applicator implements for liquid chemicals and fertilizers commonly include a vehicle, usually self-propelled, with a tank and a plurality of spray nozzles in fluid communication with the tank. Often, the nozzles are supported on a boom structure which extends perpendicularly outward on both sides of the implement. Boom structures which are immovably fixed to the rear of the applicator implement are known in the agricultural industry. Hard-mounted boom structures ordinarily extend no farther than 25 feet on either side of the implement for a swath width of 50 to 55 feet. Boom structures having a support wheel at the end of the boom sometimes extend to 40 feet on each side of the implement.
The length of unsupported, hard-mounted boom structures is limited by the weight and strength of materials used to construct the boom structure. Not only is a boom structure cantilevered from the implement, but it is also subjected to severe bouncing-type impacts each time the implement strikes a rock or furrow in the field. A trade-off exists between structural strength and the capacity of the implement to carry the weight of an increased volume of structural materials. In known devices, the compromise has resulted in boom structures of approximately 25 feet as indicated.
Wheel-supported boom structures often carry more structural materials. However, wheel-supported boom structures continue to be susceptible to impact breakage because of boom bouncing as the wheels follow the contour of a field. Additionally, it is often difficult to control support wheels which are spaced a distance from the implement vehicle.
The width of known applicator boom structures is limited for another reason. Hard-mounted boom structures are held in a fixed relationship with the implement. If the implement strikes a rock or furrow and, consequently, is raised or lowered on one side, the boom structures assume an inclination angle relative to the ground. One end of the boom may actually contact the ground, while the other end may be several feet higher than usual above the ground. The result may be boom structure breakage or an ineffective or possibly detrimental spray pattern. In like manner, when the implement traverses a hillside, the end of the boom structure on the downhill side may contact and dig into the ground. The end of the boom structure on the uphill side may extend several feet higher above the ground than recommended. Again, boom structure breakage or a detrimental spray pattern may result. A poor spray pattern translates into poor crop yield.
Boom structures having support wheels are also subject to delivering poor spray patterns in that the wheels may not travel at a uniform speed and are subject to bouncing. Whenever a support wheel accelerates or decelerates relative to the implement, the chemical or fertilizer applied will be lesser or greater, respectively. Also, whenever the wheel causes the boom structure to bounce, the spray pattern will again be affected.
In addition, known boom structures for implement applicators, whether hard-mounted or wheel-supported, are maintained at a constant elevation with respect to the ground. It is ordinarily a laborious and time-consuming task to change the elevation when moving the applicator implement from one field to another.
A need exists, therefore, to stabilize boom structures of implement applicators to reduce the possibility of boom structure breakage and to insure uniformly efficient spray patterns. Furthermore, any increase in width of boom structures without loss of efficiency would result in less fuel usage and operator time expended.